The scrubber dilemma: choices and the impact of selecting the optimum hull coating

The IMO sulphur cap is fast approaching, and all vessels will need to limit their sulphur emissions to 0.5 per cent from the current limit of 3.5 per cent on 1 January 2020. Shipowners and operators fundamentally have three viable options in order to comply with this new regulation; to burn low sulphur bunker fuel oil (LSFO) instead of the current high sulphur fuel oil (HSFO); to continue to burn HSFO and install a scrubber in the vessel’s funnel to remove the sulphur before the exhaust is released into the atmosphere; or to install engines that burn LNG instead.

LNG exhaust contains almost zero sulphur content, but realistically LNG engines are only suitable for newbuild vessels. Even though it is technically possible to refrofit existing vessels, this is a costly and time-consuming process that most shipowners will not consider.

So that leaves us with the other two options. On the one hand burning LSFO is an easy choice but the price differential between LSFO and HSFO is likely to be significant. What’s more there are doubts as to the supply and availability of sufficient quantities of LSFO.

On the other hand, installing a scrubber will allow a vessel to continue to burn HSFO but at a high initial investment. It has been estimated that installing this equipment will likely cost between USD 2 to 8 million per vessel, which is no small sum. The vessel will also need to go into dry dock for the installation which takes it out of service (and off-hire) for two to three weeks. Added to the mix is that there is currently a shortage of scrubbers and dry dock availability which presents further challenges. Once installed however savings will be made, in time, and pay for the upfront investment made.



What role does a coating play?

Whether installing a scrubber or taking the decision to burn LSFO, the choice of hull coating can have a significant impact. It has been proven that by selecting an optimum hull coating fuel usage is reduced and this is irrespective of what fuel is being burned. When a ship’s hull suffers from a build-up of fouling the engine needs to produce more power to move the ship through the water at a given speed. This requires more fuel to be used and consequently more emissions are released.

This is where the right solution can help as an effective hull coating minimises speed loss. Speed loss is the difference in speed achieved by a vessel with a clean hull as compared with the same vessel with a fouled hull when the engine power output is identical.

Minimising speed loss

Using a VLCC as an example, if the shipowner chooses a market average hull coating, then the average speed loss over a five-year period would be around 18 per cent. Selecting a premium coating (such as worldwide coating manufacturer Hempel’s Globic 9500 or Hempaguard X7) the speed loss is significantly reduced to just 1.4 per cent over the same five-year period. This corresponds to the same shipowner achieving a 13.5 per cent fuel saving over five years.

Using an optimum hull coating will improve efficiency when burning either HSFO or LSFO. The costs savings can be used to payback the investment in installing a scrubber, or the cost of using the more expensive LSFO.

It is now time for shipowners to decide on how they plan to comply with the IMO’s impending sulphur cap. Whilst we cannot advise on which option to select, the application of a premium hull coating can assist shipowners to offset the associated costs. Without question, opting for a high-performance hull coating will deliver significant cost benefits over a market-average alternative, and this is irrespective of which sulphur compliance option is selected.

Posted 13 May 2019

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By Andreas Glud, Group Segment Manager, Dry Dock, Hempel A/S

By Andreas Glud, Group Segment Manager, Dry Dock, Hempel A/S

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